1. Field of the Invention
The present invention relates generally to a control system for a semiconductor processing apparatus. More particularly, the invention relates to a control system for monitoring input parameter values supplied to the semiconductor processing apparatus.
A claim of priority is made to Korean Patent Application No. 2005-10555 filed on Feb. 4, 2005, the disclosure of which is hereby incorporated by reference in its entirety.
2. Description of the Related Art
Semiconductor devices are generally fabricated by a series of fabrication processes performed under highly specific conditions. The fabrication processes may include, for example, photographic and/or chemical processing steps used to create electrical circuits on a semiconductor wafer. The processing conditions may include, for example, timing information, chemicals, temperatures, and so forth, which are used for each processing step. Collectively, the series of processes and associated processing conditions used to form a semiconductor device may be referred to as a “recipe” for fabricating the device.
A recipe for fabricating a semiconductor device is generally stored in a semiconductor processing apparatus used to perform the fabrication processes. The recipe typically manifests itself as a set of input parameter values related to the processes and processing conditions and supplied to the semiconductor processing apparatus.
In order to ensure that the semiconductor device is fabricated correctly, the input parameter values are usually validated before and/or during the fabrication processes to ensure that they will lead to predictable and acceptable results. For example, the input parameter values may be validated by inspecting preset parameter values on the semiconductor processing apparatus prior to performing a fabrication process. In addition, the input parameter values may be validated by monitoring variations of the parameter values while the fabrication processes are being performed.
FIG. 1 is a block diagram illustrating a conventional control system 100 for a semiconductor processing apparatus.
Referring to FIG. 1, conventional control system 100 comprises a control server 20 and an operator interface 30. A plurality of semiconductor processing apparatuses 10 arranged in fabrication lines are connected to control server 20 through a communication interface (e.g., a wired or wireless digital connection, network lines such as twisted pair cables, or the like). Operator interface 30 is also connected to control server 20 through a communication interface.
An operator uses operator interface 30 to perform a “track-in” operation. The term “track-in” refers to an operation whereby one of semiconductor processing apparatuses 10 is selected through operator interface 30. Typically the selection is made by a human operator. However, performing a track-in operation does not necessarily require a human operator. The track-in operation is performed by providing an input specifying a particular semiconductor processing apparatus 10 to control server 20 via operator interface 30.
Control server 20 runs a control program adapted to control semiconductor processing apparatuses 10. The control program includes a range specification for input parameter values supplied to semiconductor processing apparatuses 10. The range specification is used to determine whether the input parameter values supplied to semiconductor processing apparatuses 10 are proper. For example, the range specification may include upper and lower limits for each of the input parameters. Accordingly, input parameter values outside of the upper and lower limits are considered improper.
FIG. 2 is a flowchart illustrating a conventional method 50 of controlling a semiconductor processing apparatus using the control system shown in FIG. 1. Throughout this description, method steps are designated within parentheses (XXX) to distinguish them from system elements, like those shown in FIG. 1.
Referring to FIGS. 1 and 2, an operator sends a message specifying a specific semiconductor processing apparatus 10 to control server 20 through operator interface 30 (51). Control server 20 requests that the selected semiconductor processing apparatus 10 send a recipe including input parameter values (52) to control server 20. The recipe may include, for example, current preset parameter settings for the selected semiconductor processing apparatus 10.
Once the selected semiconductor processing apparatus 10 sends the recipe to control server 20, control server 20 uses the control program to determine whether or not the input parameter values in the recipe are proper according to the range specification (step 53). Based on a result of this determination, control server 20 determines whether or not to approve the track-in operation and whether or not to start fabrication processes specified by the recipe. Collectively, these determinations are referred to as an interlock decision step.
Where the input parameters are improper according to the range specification, control server 20 disapproves the track-in operation (step 54). In other words, the selection of the particular semiconductor processing apparatus 10 is cancelled. In addition, control server 20 also typically generates interlock signals, causing any fabrication processes specified by the recipe to be cancelled, i.e., not performed (55).
Where the input parameters in the recipe are proper according to the range specification, control server 20 approves the track-in operation, i.e., the selection of the semiconductor processing apparatus 10 (56). Then, the selected semiconductor processing apparatus 10 starts performing any fabrication process(es) specified by the recipe (57).
Unfortunately, the conventional control system for a semiconductor processing apparatus and its associated methods have at least the following drawbacks. First, control server 20 only verifies whether or not the input parameter values are between upper and lower limits. Accordingly, control server 20 fails to consider undesirable variations of the input parameter values or undesirable combinations of input parameter values, as examples. This can cause a number of problems. For instance, although the input parameter values may remain within the upper and lower limits, excessive variations of the input parameter values may cause unexpected failures during fabrication processes. Conventional control server 20 fails to address such variations of the input parameter values during fabrication processes.
Second, conventional control server 20 is typically limited in both data memory capacity and data processing capacity. As a result, where a large amount of data needs to be processed within a limited amount of time, control server 20 may fail to meet processing deadlines. For example, control server 20 may fail to verify a large number of input parameter values within a short period of time. Accordingly, control server 20 may fail to detect certain improper parameter values. In such cases, control server 20 may be configured only to verify a certain subset of the input parameter values of semiconductor processing apparatuses 10. Alternatively, the total number of input parameter values to semiconductor processing apparatuses 10 may simply be limited.
Third, modifying the range specification in the control program generally requires modifying the control program itself.
Fourth, due to the limited data memory in control server 20, it may be difficult to organize the input parameter values sent to control server 20 into a database format.
Fifth, where a particular recipe not registered with the control program is received by control server 20, the conventional control system has no way to verify the input parameter values in the non-registered recipe. Such a non-registered recipe may be a completely new recipe or an earlier used recipe.
Due to at least these shortcomings of the conventional control system for a semiconductor processing apparatus and its associated methods, an improved control system and new methods are needed.